Prior art methods and devices for temporarily blocking the flow of fluid in a pressurized pipe with retained sealing relative to the ambient are disclosed, for example, in Swedish patent publication 8605208-1. In these devices, the external diameter of the expandable body, in the form of a cylindrical rubber balloon attached to the blocking unit, has a specific maximum size in relation to the internal diameter of the pipe to be blocked because of practical limitations in the ability of the balloon to expand. This is a major disadvantage, since a plurality of different dimensions are required for the installation unit, blocking unit and rubber balloon to accommodate pipes of different sizes. Another major disadvantage is that when the blockage of, for example, two inch pipes or larger is involved, the blocking unit, drill and rubber balloon must be so large that hand drills can no longer be used to make the hole in the pipe, and large, stand-mounted power drills become necessary. Since the pipes in question are often water and heating pipes mounted near walls in buildings, the lack of space rules out the use of drills of the requisite size.
The prior art method is only.intended for temporarily blocking the flow in a pipe and the expandable body is removed after blocking.
Another disadvantage with respect to the prior art method is that the shape of the expandable body changes after a period of time in the inflated state so that the balloon is unable to fully assume its original shape. Its external diameter is then larger than the hole in the pipe-through which the expandable body is to be removed. This means that the expandable body could detach from the blocking unit during removal and get left behind in the pipe.